An alternative physical explanation of the Hall-Petch relation

A new physical model to explain the Hall-Petch relation is proposed. The main assumption is that the Hall-Petch slope (k(y)), is proportional to the work required to eject dislocations from grain boundaries. The model predicts a traditional Hall-Petch relation down to a grain size of about 5 mum, below which a deviation from linearity is observed. The strengthening peaks in the vicinity of 30 nm, and further grain refinement leads to softening. A semi-empirical equation is developed, which takes into account the effects of grain boundary strain energy. The model is applicable to both equiaxed and non-equiaxed grain structures. (C) 2003 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.